The FBI has singled out Chinese-Americans as part of a controversial insider-threat reduction program that has sought to flag alleged efforts to manipulate polygraph tests, according to a leading national security defense attorney.

"The government reacts with this sledgehammer instead of laser precision to determine who would be an insider threat which is very difficult to predict," said Mark Zaid, who has several clients with ongoing disputes involving intelligence agencies including the FBI. "They're sacrificing tons, dozens and dozens of Americans who're doing nothing but their jobs, and the FBI is one of the worst to do this."

Zaid argues the program is flagging potentially innocent people based on a questionable standard.

One of Zaid's clients -- who asked not to be identified for fear of further retaliation – explained how it works. The client said, in their case, an evaluator alleged during a routine polygraph that the FBI employee had used "counter measures" to affect the accuracy of the test.

The National Center for Biotechology Information describes "counter measures" as changes in behavior designed to manipulate the test results. They include the use of a "physical countermeasure (biting the tongue or pressing the toes to the floor) or a mental countermeasure (counting backward by 7) among others."

Tom Mauriello, an adjunct lecturer and laboratory instructor for the Department of Criminology and Criminal Justice at the University of Maryland, further explained that, “No one in the polygraph community has really agreed on a specific definition, but I would say a countermeasure (CM) is the intentional manipulation of the polygraph subject's physiology by the subject with the explicit intent to distort their reactions.”

Agencies have sought to flag the use of “counter measures” amid the fear of an insider threat from China, in the wake of high-profile breaches including the compromise of more than 21 million records at the Office of Personnel Management.

Mauriello said the greatest concern is security-clearance applicants "intentionally trying to beat the test in order to gain access to sensitive and classified information for purposes of espionage, etcetera. That is the person the process is trying to identify, not an overly nervous person who is just trying to pass the test."

But critics suggest ordinary workers are getting caught up in the process. Zaid said once a government employee is accused of countermeasures, it becomes difficult to prove a negative.

"All this device is doing is measuring your breathing, your heartrate, your galvanic sweat response. And it's determining based on that if you're telling the truth or not,” he said. “And it's determining are you telling the truth depending on where your physiological response falls."

Mauriello said there is room for confusion. "It is my opinion that when a subject is being told that they are not passing their polygraph test, their attempt to try to help themselves is being labeled as them using countermeasures rather than them just trying to pass the test," he said.

Asked if the tool is open to abuse, Mauriello emphasized, "I don't think there is any intentional abuse by anyone in the polygraph community in regards to this matter. They are trying to use the polygraph effectively for what it is, just an ‘investigative tool.’ I believe it is a lack of collective understanding and definition of what a countermeasure is and maybe overzealous examiners looking for something that is not there."

After being accused of using countermeasures, the federal employee who spoke with Fox News said they were placed on unpaid leave -- and with a suspended clearance, could not seek other work in the national security sector. Both Zaid and the employee said there is no timeline on when an appeal should be resolved. In the individual's case, the first level of review took more than a year.

"You don't see any leadership inside the agencies or on the Hill to take a look at this. There's still thankfully a small number of cases," Zaid said. "They are on unpaid leave for two or three years. There's no voice for these people. When you look at it you have anything but utter disappointment and sadness and pathetic feelings for how our system works."

Polygraphs are given every five years to most security-clearance holders. As a way to mitigate the risk, some employees are polygraphed on a more frequent basis due to factors such as birth outside the U.S., foreign-born parents, frequent overseas travel or financial trouble.

Fox News was told that about 18 months ago, the FBI changed its procedures, and those accused of countermeasures were given the opportunity to take at least one more polygraph. Whether their clearance was suspended, and they were placed on unpaid leave, was decided on a case-by-case basis.

Fox News asked the FBI for comment on the allegation that the review process was slow, and the use of countermeasures was too subjective. Fox News also asked the bureau if there is publicly available data to test whether Asian Americans are being wrongly singled out.

The FBI did not provide data so the claim could not be tested. An FBI spokesperson told Fox News in a statement: “All employees undergo a periodic reinvestigation to determine whether a person’s continued access to classified information is clearly consistent with national security. The polygraph examination augments the FBI security process as one of many tools utilized when collecting information through investigation for making access eligibility determinations. Such determinations are not based solely on the result of a polygraph examination.”

With his client now in a second year of unpaid leave, Zaid said the issue appears much larger. "As much as we are supposed to be protecting these ethnic groups from discrimination," Zaid said, "once you start seeing that, you have to raise your eyebrows and ask ‘are we racially profiling these individuals’?”